JPS5845708B2 - Electrophotographic materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic material, particularly an electrophotographic material having an intermediate layer between a support and a photosensitive layer.

Conventionally, in electrophotographic materials in which a photoconductive photosensitive layer is provided on a conductive support, an intermediate layer is interposed between the support and the photosensitive layer.

This intermediate layer has a large effect on the electrophotographic performance of the electrophotographic light-sensitive material, and has a large influence on the electrophotographic performance of the electrophotographic material, such as the chargeability of the photosensitive layer, the dark decay characteristics, the magnitude of the residual potential, the sensitivity, and therefore the gradation of the electrophotographic image obtained. It is greatly related to tonality and image quality,
Furthermore, it is greatly related to physical properties such as abrasion resistance, corona impact resistance, and moisture resistance when used in a repetitive transfer type electronic copying machine.

Such an intermediate layer must have sufficient adhesion and appropriate conductivity, and conventionally, for example, casein,
polyvinyl alcohol, carboxymethyl cellulose,
Contains ethyl cellulose, vinyl acetate, or solid substances such as silica powder or clay dispersed therein to improve conductivity and adhesive properties, or a compound having a quaternary ammonium group in the resin. An intermediate layer is formed in such a manner as to force it.

However, conventional intermediate layers generally have the disadvantage that their mechanical strength, in particular their abrasion resistance, is low.

This drawback causes great problems, especially when forming other layers on this intermediate layer, such as photosensitive layers or conductive layers, especially in the production of electrophotographic materials.

That is, the formation of such a layer is usually performed by applying a liquid material and drying the resulting coating film, and from various points of view it is optimal to use a wire bar coater to achieve the above-mentioned application. .

However, when applying the liquid onto the intermediate layer using a wire bar coater, the wire portion of the wire bar coater is moved while being in contact with the surface of the intermediate layer, so that scratching time remains on the surface.

As a result, the properties of the photosensitive layer are deteriorated due to the rings, and the resulting electrophotographic image (unevenness occurs), resulting in a decrease in image quality.

Furthermore, since the mechanical strength of the intermediate layer is low, the electrophotographic light-sensitive material naturally also has low mechanical strength and has a short life when used in a repeat transfer type electronic copying machine.

Furthermore, conventional intermediate layers do not necessarily have sufficient adhesion, and therefore it is difficult to completely and reliably achieve adhesion to the support or photosensitive layer to be integrally adhered to the intermediate layer. As a result, the intermediate layer peels off during the production of electrophotographic materials, and the resulting electrophotographic materials have low charging characteristics or high residual potential, making it difficult to obtain sufficient density for electrophotographic images. cannot be obtained, and durability is low.

In view of the above, an object of the present invention is to provide an intermediate layer which has high mechanical strength, particularly abrasion resistance, and which does not cause weirs on the surface even when a coating film is formed on the surface using a wire bar coater. An object of the present invention is to provide an electrophotographic material having the following properties.

Another object of the present invention is to provide an intermediate layer which has sufficient adhesion and can therefore be easily and reliably integrated with the support or other layers, and which has excellent electrical properties and durability. The purpose of the present invention is to provide an electrophotographic light-sensitive material.

Still another object of the present invention is to provide an electrophotographic light-sensitive material having an intermediate layer that is sufficiently hard, has great durability, has excellent moisture resistance, and has appropriate flexibility. It is in.

Another object of the present invention is to provide an electrophotographic light-sensitive material that has an intermediate layer that has high mechanical strength and has a favorable effect on image forming properties, and is therefore capable of forming good electrophotographs.

In order to achieve the above object, the present invention provides an intermediate compound containing a compound having a hydroxyl group, an amine group, or both, and a quaternary ammonium group (hereinafter referred to as "compound A"), and an epoxy resin. A layer is interposed between the support and the photosensitive layer.

More specifically, compound A and an epoxy resin are mixed and dispersed in a suitable solvent, and the resulting fluid is applied to the surface of a conductive support, dried, and heat-treated as necessary. By curing the coating film, an intermediate layer is formed on the support, and a photosensitive layer is formed on this intermediate layer, thereby producing an electrophotographic light-sensitive material.

Since the electrophotographic light-sensitive material of the present invention is as described above, various benefits can be obtained by the intermediate layer.

That is, the epoxy resin in the intermediate layer has a crosslinked network structure in which the epoxy groups react with the hydroxyl group and/or amino group of the compound A during the curing process,
Therefore, this intermediate layer is sufficiently hard and has excellent mechanical strength, particularly excellent abrasion resistance.

Therefore, even when applying a photosensitive liquid or other layered acid solution to form a photosensitive layer or other layer on the intermediate layer, there is almost no risk of forming a weir on the surface of the intermediate layer. A wire bar coater can be used for the coating without special consideration, making it possible to manufacture electrophotographic light-sensitive materials easily and efficiently, and the weir on the surface of the intermediate layer prevents the occurrence of unevenness in electrophotography. It becomes an electrophotographic light-sensitive material without.

Further, since the intermediate layer has a high mechanical strength, a long life can be obtained for use in a repeat transfer type electronic copying machine.

Moreover, since epoxy resins are polymerized by addition polymerization,
Unlike resins that harden through condensation polymerization, they do not generate water or other substances or reduce volume, and therefore do not cause deformation of the photosensitive layer or deterioration of properties due to water or the like.

Furthermore, since epoxy groups react particularly with amino groups at low temperatures, there is no need for high-temperature heat treatment, and various problems associated with high-temperature treatments can be prevented.

Further, since the intermediate layer in the present invention contains an epoxy resin, it has a large adhesive force, and therefore has sufficient integrity with the support etc., and can prevent non-uniformity of properties due to incomplete integrity. The photosensitive material as a whole has high strength and durability.

This advantage is particularly noticeable when the support is made of metal.

Further, due to the crosslinked structure of the epoxy resin, water resistance is improved and high electrical durability is obtained, which is effective in preventing white spots from occurring in electrophotographic images due to dielectric breakdown and the like.

Of course, since the intermediate layer contains Compound A having a quaternary ammonium group, the resulting electrophotographic performance is excellent.

For example, the electrical and physical properties of the photosensitive material do not change even in a dry atmosphere, so images without fog can be obtained, and the durability is improved, so fatigue and deterioration are reduced.

In another example of the present invention, the intermediate layer contains, in addition to the epoxy resin and compound A, a compound having an incyanate group (hereinafter referred to as "compound B").

In such an intermediate layer, the isocyanate group of compound B is also bonded to the epoxy resin, and as a result, the photosensitive material has appropriate flexibility.

This effect is because if the proportion of epoxy resin in the intermediate layer is high, the intermediate layer becomes hard but brittle.
In such a case, O is preferable because it can prevent brittleness.

In the above, the ratio of the epoxy resin to the compound A and the compound B can be determined, for example, in an equivalent relationship between the epoxy group in the epoxy resin and the functional groups of the compound A and the compound B, that is, the hydroxyl group, the amino group, and the isocyanate group.

However, it is not necessary to react all the functional groups with the epoxy groups, nor is it necessary to react all the epoxy groups with the functional groups.

Therefore, it may be determined by taking into consideration the characteristics of the resulting interlayer of the tatami bone.

Further, in the present invention, it is of course possible to incorporate other substances into the intermediate layer as long as the above-mentioned effects are not lost.

Next, the substances used in the present invention will be specifically explained.

Structural formulas of representative examples of epoxy resins are shown below, but various types can be used in the present invention.

For example, it does not matter whether it is liquid at room temperature or whether it has a molecular weight (usually 300 to 200,000).

Representative examples of compound A are as follows.

However, nl, n2 and n3 represent the polymerization mol% of each monomer.

In addition to the above, commercially available products include “Nirekondo B-146”,
“Nirecondo B-134DJ”Nirecondo B-14
4LJ (also manufactured by Soken Kagaku Co., Ltd.) can also be mentioned.

Further, representative examples of compound B are as follows.

B-1) Diphenylmethane-p,p'-diisocyanate B-2) Polyisocyanate which is a polymer of 1) B-3) Reaction product of l-luidine isocyanate and trimethylolpropane B-4) Tolylene diisocyanate 13 -5) 3,3'-dimethyl-diphenyl4,4'-
Diisocyanate B-6) 3,3'-dimethyl-diphenylmethane 4゜4
'-Diisocyanate B-7) Metaphenylene diisocyanate B-8) Triphenylmethane-triisocyanate B-9) 4'-Tolylene-diisocyanate B-10) Hexamethylene diisocyanate 0CN
(CH2)60ON Commercial product: "Desmodur H" manufactured by Nippon Polyurethane Co., Ltd. B-11) Naphthylene-1,5-diisocyanate B-
12) 1-Incyanate-6-N,N-dicarboxyhexamethylene-isocyanate-n-hexane Examples of the present invention will be described below.

Example 1 Cadmium sulfide microcrystals (average particle size lμ) 10. (L9 thermosetting acrylic resin HR-1166,0,!9 (manufactured by Mitsubishi Rayon Co., Ltd. solid content 50%) Butylated melamine resin J-8200,8,!i' (manufactured by Inu Nippon Ink Co., Ltd. solid content 60%) Epoxy Resin "Epicoat+828j O, L9 (manufactured by Shell Petrochemicals)" Fluorine compound FC-430 (manufactured by 3M) 0.089 butyl acetate 7 ml or more of the substances were mixed and dispersed by ultrasonic dispersion to obtain a photosensitive liquid.

This photosensitive solution was applied onto the surface of a temporary support made of a polyethylene terephthalate film with a thickness of 100 μm using a wire bar coater so that the film thickness after drying would be 25 μm, and then dried, followed by heat treatment at a temperature of 130° C. for 30 minutes. This gave the photosensitive layer its shape.

Next, use the epoxy resin “Epicoat Φ828J 10
g Compound A (example A-3) 100. ! i
+ Compound Compound Example B-3) 10. ! i
A 10% by weight solution is prepared by dissolving the mixture of the three components + in a mixed solvent of methyl ethyl ketone and methyl alcohol in a ratio of 7:3, and this is used as an intermediate layer forming liquid on the surface of the photosensitive layer after drying. It was coated and dried to a film thickness of 5 μm, and then heat treated at 100° C. for 1 hour to form an intermediate layer.

Furthermore, conductive car H8-500 (manufactured by Asahi Rikikanshi Co., Ltd.)7. Og
Thermosetting acrylic resin HR-11640g toluene
A dispersion obtained by thoroughly dispersing 150 ml of the mixture of the three in a ball mill was applied onto the surface of the intermediate layer using a wire bar coater, dried, and heat-treated at a temperature of 130° C. for 1 hour to form a conductive layer with a thickness of 50 μm. The layers were shaped to form an intermediate photoreceptor.

A composite film obtained by laminating a 50 μm thick polyester film and a 50 μm thick polyethylene film to this intermediate photoreceptor is laminated on the surface of the conductive layer as the main support, and then the temporary photoreceptor is laminated onto the surface of the conductive layer. The support was peeled off to expose the photosensitive layer, thereby producing an electrophotographic material having a smooth surface.

This is designated as sample 1. Example 2 Epoxy resin I'-r Epoxy YH-301J11 (manufactured by Tobu Kagaku Co., Ltd.) Compound A3 Example A-12) 101 Compound B (
Example B-8) Using the mixture of the three substances in 10.9, strain O to prepare an intermediate layer forming liquid as in Example 1, and use the same method as in Example 1 except that this intermediate layer forming liquid was used. This led to the creation of electrophotographic materials.

This is designated as sample 2. Example 3 Epoxy resin Giant Piquat +828J 10. !
i+ compound Compound Example A-13) 10 (1 Compound B (Example B-9) An intermediate layer forming solution was prepared in the same manner as in Example 1 using 10 g of a mixture of the three, and this intermediate layer was An electrophotographic light-sensitive material was prepared in exactly the same manner as in Example 1 except that the forming liquid was used.

This is designated as sample 3. Example 4 Epoxy resin I'/A epoxy YH-301J 1
0. ! i+ compound Compound example A-7) 10
Example 1 was repeated, except that 0g of the mixture of the two was dissolved in a mixed solvent of methyl ethyl ketone and methyl alcohol in a ratio of 8=2 to make a 10% by weight solution, and this was used as the intermediate layer forming liquid. An electrophotographic material was prepared in exactly the same manner.

This is designated as sample 4.

When the above samples 1 to 4 were installed in a repeat transfer type electronic copying machine and a continuous copying test was carried out, in each case, even after 7,000 copies were made, electrophotographs with excellent images were obtained.

On the other hand, in the material for making the intermediate layer in Examples 1 to 4, thermosetting acrylic resin HR was used instead of epoxy resin.
-557 (manufactured by Mitsubishi Rayon Co., Ltd.) were used in exactly the same manner as in Examples 1 to 4, respectively, to prepare four types of electrophotographic materials corresponding to Samples 1 to 4, respectively. When a continuous copying test was conducted in the same manner as described above, in each case, a straight line unrelated to the original image was seen in the image from the first copy of the electrophotograph, and this straight line gradually became darker as copies were repeated. I got thicker.

In the production of electrophotographic photosensitive materials, when applying a liquid to form a conductive layer on an intermediate layer, a wire bar coater creates a linear gap on the surface of the intermediate layer, and this gap causes the potential characteristics of the photosensitive layer. This is because it changes according to the ring.

In addition, examples 1 to 3 were used in which a stainless steel sheet was used instead of the composite film as the main support and no conductive layer was formed.
Similarly to 4, four types of electrophotographic light-sensitive materials according to the present invention,
Four types of electrophotographic light-sensitive materials were prepared corresponding to comparison samples, but in all of the latter, when the temporary support was peeled off in the final step, the intermediate layer and the main support were peeled off, and the temporary support was removed. It was quite difficult to remove the body.

However, there were no such difficulties with the former.

This is because the intermediate layer in the present invention has sufficient adhesion to the gold layer support.

Example 5 Epoxy resin H epoxy resin-434J 7g
(Manufactured by Tobu Kagaku Co., Ltd.) Compound A (Example A-3) 10 (1 Compound B (Example B-3) 10. Substances with iF or higher are mixed, and this mixture is mixed with methane.

A 10% by weight solution was prepared by dissolving ethyl ketone and methyl alcohol in a mixed solvent at a ratio of 7:3, and this solution was applied to the surface of a support made of stainless steel sheet so that the thickness after drying was 5μ. Apply and dry, temperature 90
A heat treatment was performed at .degree. C. for 1 hour to form an intermediate layer on the support.

Next, a photosensitive liquid similar to that in Example 1 was applied and dried on the surface of the intermediate layer using a wire bar coater so that the film thickness after drying was 25 μm, and then heat treatment was performed at a temperature of 130° C. for 30 minutes. A photosensitive layer was formed, thereby producing an electrophotographic photosensitive material.

This is designated as sample 5.

The epoxy resin "Bayepoxy Y H343j" has the following basic structural formula.

Example 6 Epoxy resin "Epikote 1328j IOF compound example A-3') 100.!i+ or more substances were mixed, and this mixture was mixed with a mixed solvent of methyl ethyl ketone and methyl alcohol in a ratio of 1:1. An electrophotographic light-sensitive material was prepared in the same manner as in Example 5, except that a 10% by weight solution was prepared by dissolving it in the solution, and an intermediate layer was formed using this solution.

This is designated as sample 6. On the other hand, the samples were prepared in the same manner as in Examples 5 and 6, except that among the materials for making the intermediate layer in Examples 5 and 6, alkyd resin J-555 (manufactured by Dainippon Ink Co., Ltd.) was used instead of the epoxy resin. Two types of electrophotographic light-sensitive materials corresponding to Examples 5 and 6 were prepared.

These are designated as Comparative Samples 5 and 6, respectively.

Regarding the above samples 5 and 6 and comparative samples 5 and 6,
Each of these was installed in the same repetitive transfer type electronic copying machine, and a continuous copying test was conducted in an atmosphere at a temperature of 30° C. and a relative humidity of 80%.

As a result, in the test using sample 5, the number of copies was 25.
Even when the number of copies reached ,000 copies, excellent images were still formed, and in the test with sample 6, the number of copies was 22,000 copies.
Even when the number of sheets reached 0, excellent images were still obtained.

On the other hand, in the test using Comparative Sample 5, linear patterns and white spots became noticeable in the image when the number of copies reached approximately 1,000, and when the number of copies exceeded 12,000, The images no longer had any value as electronic photographs.

Also, in the test using Comparative Sample 6, defects appeared in the electrophotographic image as with Comparative Sample 5, and the effective number of copies was approximately 10.
It was 000 pieces.

In the test of the above comparative sample, it was determined from its appearance that the linear pattern that appeared in the image was due to the weir formed on the surface of the intermediate layer by a wire bar coater when applying the photosensitive liquid.

It is also believed that the white spots are due to non-uniformity of electrical properties due to insufficient adhesion between the intermediate layer and the support, or deterioration of electrical properties due to moisture.

Moreover, from the above Examples 1 to 3 and Example 5, it is preferable that the intermediate layer in the present invention contains not only the epoxy resin and the compound A but also the compound B.
It is understood that the desired effect can be achieved even when it does not contain.

As detailed above, according to the electrophotographic light-sensitive material of the present invention, it is possible to greatly improve the mechanical strength, especially the abrasion resistance, of the intermediate layer with an extremely simple structure, and to ensure sufficient adhesion of the intermediate layer. It is possible to obtain excellent properties in various respects, to obtain electrophotographs of excellent image quality, and to obtain great benefits such as being particularly suitable for use in repeat transfer type electronic copying machines.

Claims (1)

[Scope of Claims] 1. An electrophotographic light-sensitive material comprising an intermediate layer containing a compound having at least one of a hydroxyl group and an amine 7 group and a quaternary ammonium group, and an epoxy resin. 2. The electrophotographic light-sensitive material according to claim 1, wherein the intermediate layer further contains a compound having an incyanate group.